1. Do Now Classify each angle as acute, right, obtuse or straight.
1. m ˂ DBE = 35 °
2. m ˂ EBC = 80°
3. m ˂ MPL = 90°
4. m ˂ ABD = 180 °
5. m ˂ CRF= 91 °

2. 1.5: Describe Angle Pair Relationships
Geometry
1.5: Describe Angle Pair Relationships
Objective: SWBAT use special angle relationships to find angle measures.

3. Angle Relationships Complementary Angles: Supplementary Angles:
Two angles whose measures have a sum of 90°
Supplementary Angles:
Two angles whose measures have a sum of 180°

4. Example
For each number below, Angles 1 and 2 are complementary and angles 2 and 3 are supplementary. Find the missing angles. measure.

5. Supplementary & Complimentary Angles Examples

6. Angle Relationships Adjacent Angles: Linear Pair:
Angles that share a common vertex and side but have no common interior points
Linear Pair:
Two adjacent angles whose non-common sides are opposite rays.
The sum of the measures of angles that form a linear pair is 180°

8. Angle Relationships Vertical Angles: Perpendicular Lines:
Two angles whose sides form two pairs of opposite rays
* vertical angles are congruent *
Perpendicular Lines:
Two lines that intersect to form a right angle.

9. Find angle measures in a linear pair
Two angles form a linear pair. The measure of one angle is 5 times the measure of the other. Find the measure of each angle.
ALGEBRA
SOLUTION
Let x° be the measure of one angle. The measure of the other angle is 5x°. Then use the fact that the angles of a linear pair are supplementary to write an equation.

10. Vertical? Linear? Neither?

11. Vertical Angles

12. Homework
Textbook Pages # 10, 14, 17, 20, 22, 24, 26, 31, 40, 42